Miura LX Series Low NOx Steam and Hot Water Boilers

LX Series Models

Miura is known world-wide for their commitment to protecting the environment and their innovative and efficient boiler designs. Their low NOx steam and hot water boilers meet and exceed current and proposed regulations for nitrogen oxide emissions levels, as low as 9ppm NOx at 3%, corrected O2.

  • Gas fired: Natural Gas or Propane
  • High and low pressure steam options available (300 MAWP, 170 MAWP or 15 MAWP)
  • Hot water boilers are available depending on models
  • Compact, an LX 200 Boiler can fit through a standard doorway
  • Naturally low NOx (nitrogen oxides) Rating as low as: 9ppm depending on model

LX Series Model Design

The Miura LX Series design consists of rows of vertical tubes sandwiched between two rectangular headers. Both headers are encased in a castable refractory with only the tubes exposed to flame and/or combustion gases. The upper header is attached to the lower header only by the tubes. As the tubes expand and contract, the headers float up and down accordingly.

This ’floating header’ concept greatly reduces stress and allows for the use of cold feedwater without the fear of significant thermal shock. The ’leaky tube’ problems associated with firetube and bent watertube designs have been eliminated.

Low NOx “No Furnace” Boiler

Cool, soft flame wraps around the tubes from a flame spread over a large surface area. This naturally controlled burn results in unbelievably low NOx, compact size and high efficiency.

Full Steam Output In Less Than 5 Minutes

Floating headers mean fast start-up. Miura boilers produce fast steam in less than 5 minutes from a cold start-up. Standard firetubes require 1 to 1.5 hour start-up times. Miura’s unique design yields significant time and fuel savings.

Smaller is Better

Miura’s LX Series boilers occupy 50% less floor space than typical firetubes, and do not require tube pull space. Double your capacity in the same space, or reduce space requirements by half for new construction. Miura’s compact design means much smaller radiation losses and larger fuel savings.

Early Warning Scale Monitor

Scale is a problem all boilers have to deal with. Scale forms when boiler feedwater is not properly treated. Advanced scale formation acts as an insulator; only an eggshell thickness of scale results in a 10% efficiency loss, higher fuel bills and possible damage to the boiler system.

As standard equipment, all Miura LX models are equipped with a thermocouple attached directly to a tube. Should scale begin to form, the MIURA boiler will alert the operator – allowing the operator to trace and repair the source of the water hardness. The scale can be removed to restore the boiler to its original efficiencies – saving tens of thousands of dollars in wasted fuel and repair bills.

Unbeatable In-Service Efficiencies

Miura’s computer-aided design results in optimal heating surface transfer with minimal water content for fuel-to-steam efficiencies of 85%. Typical firetube designs can deliver up to 83% fuel-to-steam efficiencies. However, in actual use, Miura averages 10 to 40% fuel savings over standard firetube designs. How does a 2% difference in fuel-to-steam efficiencies translate into a 10 to 40% ACTUAL FUEL SAVINGS? Contact your local Miura representative for details.

LX-50LX-100LX-150LX-200LX-300 [7]
Utilization Horsepower [1]50HP100HP150HP200HP300HP
Maximum Pressure170 PSIG MAWP, 150 PSIG Maximum Operating (15 PSIG MAWP)
Equivalent Output [2]1,725 LB/HR3,450 LB/HR5,175 LB/HR6,900 LB/HR10,350 LB/HR
Heat Output1,674,000 BTU/HR3,348,000 BTU/HR5,022,000 BTU/HR6,695,000 BTU/HR10,050,000 BTU/HR
Efficiency (fuel to steam) [3]85% (80% without Economizer)87%
Heating Surface Area192.4 FT²269.0 FT²388.2 FT²387.7 FT²611 FT²
Operational Weight3,710 LBS6,070 LBS8,620 LBS8,620 LBS10,940 LBS
Shipping Weight4,140 LBS5,930 LBS7,920 LBS7,950 LBS11,050 LBS
Width40 in. (50 in.)38 in. (50 in.)43 in. (65 in.)43 in. (65 in.)63 in.
Length96 in. (119 in.)124 (155 in.)139 in. (142 in.)139 in. (142 in.)153
Height103 in. (147 in.)111 in. (161 in.)126 in. (131 in.)126 in. (131 in.)127
Combustion SystemProprietary Forced Draft, Step Fired Modulation Hi-Low-Off4 Position Step Burner (Hi-Low-Ignition-Off)
Ignition SystemElectric Spark Ignited, Interrupted Gas Pilot
Power Supply208, 230, 460, 575V, 3 phase, 60Hz
Max. Electrical Consumption6.5 KVA (5.0 KVA)13.3 KVA (10.9 KVA)22.1 KVA24.3 KVA (19.0 KVA)refer to installation manual 1.8
Fuel Type [4]Natural Gas or Propane (3-5 PSIG)
Gas Consumption [5]1,960 SCFH3,920 SCFH5,880 SCFH7,850 SCFH11,500 SCFH
Gas Supply Pressure3-5 PSIG Natural Gas or Propane
Main Steam Outlet Valve2 in. (4 in.)2 in. (6 in.)3 in. (8 in.)3 in. (8 in.)4 in.
Safety Valve Outlet [6]One 1 1/2 in.One 2 in.One 2 1/2 in.One 2 1/2 in.Two 2 1/2 in.
Main Water Inlet3/4 in.1 in.1 in.1 in.1 1/2 in.
Fuel Gas Inlet1 1/2 in.2 in.2 in.2 in.2 1/2 in.
Automatic Surface BlowdownOne 3/8 in.Two 3/8 in.
Manual BlowdownTwo 1 in.One 1 in. & One 1 1/4 in.
Chimney Diameter (ID)12 in.12 in.20 in.20 in.20 in.
Flame DetectorUltraviolet Flame Eye Sensor
Pressure ControlAdjustable Pressure Transducer and Switch
Liquid Volume ControlElectric Conductivity Type
Overheat ProtectionLow Water Cut Off & Thermocouple


  • Available 49 and 199 BHP rating for L.A. area.
  • Equivalent output calculated from and at 212°F (100°C) feed water at 212°F (100°C) steam.
  • Thermal efficiencies are based on high heating values of fuels at 68°F (20°C) feed water.
  • UL and c-UL approved for natural gas or propane.
  • Gas consumption based on natural gas with high heating 1004 BTU/SCF.
  • Safety valve outlet size may change depending on the pressure setting.
  • See Miura’s MI System brochure for more on how the new LX-300 zero-side-clearance layout offers the highest system capacity per square foot in the industry.

All Miura steam boilers are fully packaged and test fired at factory. Built to meet or exceed UL and ASME standards in U.S.A.; c-UL and B-51 standards in Canada. Low pressure steam is available in 50, 100 and 200HP only. California Low NOx option available